#SpringBoot #Questions

SpringBootQuestions.md

• Advantages of SpringBoot
  • Convention over configuration; makes development faster
  • Embedded containers (tomcat or jetty server); dont have to deploy them
  • lots of starter project; easy maven intergration, no version mismatch
  • reduces boilerplate code
  • create sample application quickly using sprint boot initializer
• How can you spring boot application on custom port?
  • Mention server.port in application.properties configuration file. Default port is 8080.
• How can you override default properties in spring boot?
  • Default properties can be overridden using application.properties configuration file. Like server.port
• What are the disadvantages of using SpringBoot?
• What is actuator in spring boot?
  • Helps to access current state of running application in production.
  • Provides REST endpoints to access various metrices like free memory, processors, uptime.
    • /metrics: includes free memory, processors
    • /health
    • /info
• How can you implement spring security in spring application?
  • add spring-boot-starter-security in pom.xml
  • create a spring config class that extends WebSecurityConfigureAdapter and overrides methods in it.
• What is @SpringBootApplication annotation?
  • was introduced in Springboot 1.2
  • needs to be added in main class
  • replaces 3 annotations used earlier: @Configuration, @ComponentScan, @EnableAutoConfiguration
• Why to use sprig cloud?
  • Spring cloud provides tool to developers to develop distributed system (eg: configuration management, service registration, fault tolerance using circuit breaker, distributed tracing etc.)
  • Leverage Netflix OSS
• Which version of spring boot have u used?
  • version 1.3
• How can u enable logging in sprig boot application?
  • Spring boot come with support Log4J2, log back and is pre-configured as Console output
  • To enable logging add logging.level in application.properties
    • logging.level.spring.framework=Debug
• What are starters?
  • we can add starters in pom.xml dependency section
  • all dependent jar gets downloaded, no version issues
  • A few starters
    • spring-boot-starter-web
    • spring-boot-starter-test
    • spring-boot-starter-security
    • spring-boot-starter-jdbc
    • spring-boot-starter-logging
• What is the use of spring-boot-maven-plugin?
  • this plugin provides commands to run springboot application
    • spring-boot:run
    • spring-boot:start
    • spring-boot:stop
    • spring-boot:repackage
• How can we enable auto reload of spring boot application?
  • By using Spring Boot Development Tools; add dependency(spring-boot-devtools) in pom.xml
  • when files changes in classpath, application using spring-boot-devtools will get restarted
• How can we use jetty instead of tomcat?
  Remove the existing dependency on spring-boot-starter-web and add these in.

  <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
      <exclusions>
          <exclusion>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-tomcat</artifactId>
          </exclusion>
      </exclusions>
  </dependency>
  <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-jetty</artifactId>
  </dependency>
  

• What is transitive dependency resolution management?
  • If "A" is dependent on "B" and "B" is dependent on "C". Then "A" is also dependent on "C"
  • Build tool like maven downloads all 3 jars to application classpath
  • Spring boot uses this to resolve dependencies
• What is the use of profiles?
  • Way to handle different environments (DEV, QA, PROD)
  • We can have different properties for diff env. For example, use different DB for each environment
  • Mention active profile using spring.profiles.active in application.properties
• What is the best way to expose custom configuration in Spring boot?
  • define a configuration component using @ConfigurationProperties

        @Component
        @ConfigurationProperties("basic")
        public class BasicConfiguration {
            private boolean value;
            private String message;
            private int number;
  

  • The values can then be configured in application.properties

      basic.value=true
      basic.message="testing"
      basic.number=10